Small-Amplitude Oscillations of Encapsulated Liquid Drop Interfaces

Abstract

The oscillating interfaces of an encapsulated liquid drop, which comprises an outer liquid shell and an inner gas bubble, are studied experimentally and theoretically. Using a sequential production device of encapsulated drops in liquid-liquid-gas systems, the oscillating motions of encapsulated drop interfaces are observed in detail under various flow conditions. To investigate the dynamics of the interface, the oscillations of interfaces are theoretically analyzed using a model assuming small-amplitude oscillation of the interfaces based on the experimental observations. The oscillating mode, frequency and ratio of the inner interface amplitude to outer one of the encapsulated drop are investigated quantitatively. Furthermore, the oscillation frequency o the liquid-liquid interface of the encapsulated drop in the immiscible liquid is experimentally obtained for various liquids. Comparing the theoretical results with the experimental ones, the validity of the theoretical analysis is confirmed.